Multiple cryoprobe apparatus and method

ABSTRACT

A cryosurgery apparatus is disclosed. The cryosurgery apparatus an introducer having a hollow and a distal portion, the distal portion being sufficiently sharp so as to penetrate into a body, the hollow of the introducer being designed and constructed for containing a plurality of cryoprobes each of the cryoprobes being for effecting cryoablation, such that each of the plurality of cryoprobes is deployable through the distal portion of the introducer when the distal portion is positioned with respect to a tissue to be cryoablated.

This application is a continuation of U.S. patent application Ser. No.09/860,486, filed May 21, 2001 and now U.S. Pat. No. 6,706,037, whichclaims the benefit of priority from U.S. Provisional Patent ApplicationNo. 60/242,455, filed Oct. 24, 2000, the disclosure thereof isincorporated herein by reference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method ofcryoablation, and more particularly for cryoablation using multipleprobes introduced into the body of a patient through a commonintroducer, so as to perform cryoablation of a particular volume oftissue while minimizing damage to adjacent healthy tissues.

A variety of medical conditions are preferentially treated by ablationof tissues within the body. Classically, ablation was performed usinginvasive surgical procedures requiring cutting or destroying tissuesbetween the exterior of the body and the particular site whose ablationis desired. More recently, less invasive procedures have been developed,which bring about the destruction of selected tissues using a probe orprobes which penetrate to the area to be operated, and destroy theselected tissue by transferring energy to those tissues; RF energy,light (laser) energy, microwave energy, and high-frequency ultra-soundenergy are among the forms which have been used. However all suchmethods have the common disadvantage that while transferring energy tothe tissues whose destruction is intended, they tend also to transferenergy, through conduction, convection, and other natural processes, tonearby healthy tissues as well. All such energy transfer methodsultimately result in heat release, causing complications and adverseeffects. Noticeable pain results, the functioning of nearby healthytissues is impaired, and the healthy tissues are often damaged ordestroyed. Moreover, in some cases tissues exposed to thermal energy orother forms of energy that raise their temperatures secrete substancesthat may be toxic to adjacent healthy tissues.

In contrast, cryoablation provides a number of important advantages overother ablation techniques. Cryoablation provides better control of theablated volume than is attainable using other procedures. Moreover,real-time imaging during cryoablation, using ultrasound and MRItechniques, is helpful and straightforward, since the frozen tissue isclearly seen under these imaging techniques. Also, cryoablation, unlikeheat radiation techniques, allows for repeatable and/or complementarytreatment of the affected area. Cryoablation is considered to cause lesspain to the patients. Some scientific evidence supports the conclusionthat there is less morbidity and less risk of mortality as a result ofcryoablation procedure compared to other minimally invasive andtraditional techniques. For these and other reasons, cryoablation hasrecently become a popular method for certain types of minimally invasiveablation procedures. Examples include the treatment of prostatemalignant tumors and of benign prostate hyperplasia (BPH), and thecreation of trans-myocardial channels to effect trans-myocardialrevascularization.

Yet, cryoablation procedures also have an inherent disadvantage.Cryoprobes when activated typically form at their tip what is know inthe art as an “ice ball”, a volume which is frozen by exposure to thelow temperatures developed by the cryoprobe. Unfortunately, the radiusof the volume in which total destruction of tissues is achieved (suchdestruction of tissues being the purpose of the operation) is typicallyonly half of the radius of the volume within which tissues are more orless severely damaged. Since the volume of a sphere is proportional tothe cube of the radius, the volume of total cell destruction, for aparticular ice-ball, will typically be only the order of one-eighth ofthe volume of the area that is frozen during the operation and more orless severely damaged. The disadvantage is clear: if a single ice-ballis used to destroy a selected volume, and the ice-ball is large enoughto ensure the complete destruction of that volume (which completedestruction would be desired in the case of a malignancy, for example),then a surrounding volume approximately seven times larger will be moreor less severely damaged. That surrounding volume will typically includemuch healthy tissue that would preferably be left healthy and intact. Inthe case of ablation of the prostate, for example, freezing ofsurrounding tissues using simple cryosurgical techniques will typicallydamage or destroy, and create temporary or permanent impairment of thefunction of, the prostatic urethra, the anus, and various bundles ofnerves in the prostatic area.

One method of solving this problem is taught by U.S. Pat. No. 6,142,991to Schatzberger, teaching the use of a series of ice-balls of smalldimensions, such as can be created by a two-dimensional array ofcryoprobes whose depth of penetration can be measured and controlled, soas to achieve accurate three-dimensional placement of a plurality ofice-balls, in a manner that conforms to the dimensions and form andplacement of the lesion to be destroyed. In other words, Schatzberger'sapparatus defines a volume of controllable form and dimension, forcryoablation. The ice-balls created by the apparatus are each of smalldimensions, and they are placed so as to be contiguous to one another orto overlap each other. This arrangement results in a reduction of theamount of tissue that is damaged but not destroyed, and permits moreaccurate definition of the exact form and dimensions of the ablatedtissue.

The mechanism described by Schatzberger is not, however, well adapted toevery application of cryoablation. It is relatively complex, andrequires penetration of the affected area by a multiplicity ofindividually introduced and individually handled cryoprobes. It couldnot be used, for example, in the context of cryoablating benign prostatehyperplasia (BPH) through the urethra, a relatively non-invasivetreatment method described in U.S. patent application Ser. No.09/301,576, filed Apr. 29, 1999, and incorporated herein by reference.That procedure requires an apparatus which is both more simple and morecompact than that described by Schatzberger, in that the procedurerequires the operating portion of the cryogenic apparatus to beintroduced to the area of the lesion by means of a cystoscope, in orderto reduce reducing trauma to healthy tissue.

Thus there is a widely recognized need for, and it would be highlyadvantageous to have, a method and apparatus for cryoablation thatprovides for the destruction of a defined volume of tissue, yet whichminimizes damage to adjacent tissues. It would be further advantageousto have a method of cryoablation using an apparatus that creates such anextended volume of cryoablation yet is contained within a singleintroducer. It would be yet further advantageous to have such anintroducer which could be introduced through an operating channel of acatheter or cystoscope, enabling it to reach the proximity of the regionto be treated with a minimum of trauma to intervening tissues.

Referring now to another aspect of prior art, two-stage heating andcooling has successfully been used in surgical cryoablation systems,particularly in two-stage cooling of a high-pressure gas used to achievecryogenic temperatures using Joule-Thomson heat exchangers. Two-stagecooling presents the advantages of more rapid and more efficient coolingthan would be possible in a single Joule-Thomson cooling stage. In U.S.Pat. No. 5,993,444 to Ammar a cryogenic probe utilizes two stages ofJoule-Thomson cooling to achieve low temperatures at the operating endof the probe. Ammar describes, however, a single probe so cooled.

Schatzberger, in the patent previously cited, describes two-stagecooling in a multi-probe system. In FIG. 6 a Schatzberger teaches aplurality of cryosurgical probes connected by flexible connectors to acommon housing which includes a pre-cooling element for pre-cooling thehigh-pressure gas flowing to the probes, this element being preferably aJoule-Thomson heat exchanger used as a cooler. Schatzberger's systemthus utilizes two-stage cooling, with pre-cooling taking placeextracorporeally in the housing and a second cooling stage taking placein each individual cryoprobe. Furthermore, the mechanism Schatzbergerdescribes has the disadvantage that the pre-cooled gases must betransported a considerable distance between the housing and the probe,and the conduit connecting the probe to the housing, which must remainflexible, must also be thermally insulated.

Consequently, it would be further advantageous to have a cryoablationapparatus and method which enables the pre-cooling of a plurality ofcryoprobes within a single introducer, such that the pre-cooling stageof a two-stage Joule-Thomson heat exchange process can take place inclose proximity to a second stage of cooling which takes place withinthe individual cryoprobes.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided acryosurgery apparatus comprising an introducer having a hollow and adistal portion, the distal portion being sufficiently sharp so as topenetrate into a body, the hollow of the introducer being designed andconstructed for containing a plurality of cryoprobes each of thecryoprobes being for effecting cryoablation, such that each of theplurality of cryoprobes is deployable through the distal portion of theintroducer when the distal portion is positioned with respect to atissue to be cryoablated.

According to further features in preferred embodiments of the inventiondescribed below, the introducer comprises a cooling device designed andconstructed to cool the hollow of the introducer, and a heating devicedesigned and constructed to heat the hollow. The cooling device andheating device may be a combined heating/cooling device, such as aJoule-Thomson heat exchanger.

According to still further features in the described preferredembodiments, the introducer includes a heating and cooling device forpre-heating and pre-cooling gasses which are passed through at least aportion of the introducer and are subsequently delivered to at least oneof the cryoprobes. The heating and cooling device will preferably be aJoule-Thomson heat exchanger. The introducer will further comprise aheat-exchanging configuration for exchanging heat between a gas passedto at least one of a plurality of cryoprobes and the heating and coolingdevice. A thermal sensor, such as a thermocouple, will preferably beused to monitor temperature in the hollow.

According to still further features in the described preferredembodiments, the introducer is designed and constructed to be coupled toat least one high-pressure gas source, the gas source being coupleableto a Joule-Thomson heat exchanger having a Joule-Thomson orifice in theintroducer. The gas source may be a source of at least one gas selectedfrom a group consisting of high-pressure argon, high-pressure nitrogen,high-pressure air, high-pressure krypton, high-pressure CF₄,high-pressure N₂O, and high-pressure carbon dioxide. The gas source mayalso be a source of high-pressure helium. The introducer is designed andconstructed so as to facilitate exchange of heat between two temperaturestates of gas from the high-pressure gas source, gas in a first statebeing at a first temperature prior to passing through the Joule-Thomsonorifice, and gas in a second state being at a second temperaturesubsequent to passing through the Joule-Thomson orifice.

According to still further features in the described preferredembodiments, the introducer is designed and constructed to be coupledboth to a first gas source and to a second gas source. The gas providedby the first gas source is cooled by expansion and may liquefy whenpassing through a Joule-Thomson orifice. The gas provided by the secondgas source has an inversion temperature lower than the temperatureobtained by liquefaction of gas provided by the first gas source. Theapparatus further comprises control elements for regulating a flow ofgas from the first gas source and the second gas source.

According to still further features in the described preferredembodiments, the introducer further comprises a plurality of cryoprobescontained therein. The distal end of the introducer is formed with aplurality of openings for deployment therethrough of the cryoprobes.Preferably, at least one of the plurality of cryoprobes is coolable, andthe coolable cryoprobe is also heatable. Preferably, the cryoprobescomprise a Joule-Thomson heat exchanger having a Joule-Thomson orifice,for heating and cooling the cryoprobes.

According to still further features in the described preferredembodiments, the hollow of the introducer is partitioned into aplurality of longitudinal compartments, each of the plurality oflongitudinal compartments is designed and constructed for containing atleast one of the plurality of cryoprobes.

According to still further features in the described preferredembodiments, the introducer comprises thermal insulation designed andconstructed so as to hinder the passage of heat between the hollow ofthe introducer and tissues of the body, when the introducer ispositioned within the body.

According to still further features in the described preferredembodiments, the introducer comprises a heat-exchanging configuration.The heat-exchanging configuration may include a porous matrix, which mayinclude a conduit tunneling through at least a portion of the porousmatrix, and which may include a spiral conduit integrated with theporous matrix.

According to still further features in the described preferredembodiments, the cryoprobes preferably comprise a distal operating headwhich includes a thermally conductive outer sheath having a closeddistal end and a chamber formed within the sheath, the operating headbeing adapted to be inserted into a body and to effect cryoablationthereat. The chamber serves as a reservoir for housing a fluid incontact with at least a portion of the outer sheath of the distaloperating head.

According to still further features in the described preferredembodiments, the cryoprobes are designed and constructed coupleable toat least one high-pressure gas source, and preferably to a first gassource and also to a second gas source. The first gas source provides afirst gas, which is cooled by expansion and may liquefy when passedthrough the Joule-Thomson orifice. A second gas from said second gassource has an inversion temperature lower than a temperature obtained byliquefaction of said first gas.

According to still further features in the described preferredembodiments, the cryoprobes are designed and constructed so that gasfrom the high-pressure gas source, while in a first temperature stateprior to passing through a Joule-Thomson orifice, exchanges heat withgas from the high-pressure gas source which is in a second temperaturestate subsequent to having passed through the Joule-Thomson orifice.Control elements are provided for regulating the flow of gas from thefirst gas source and from the second gas source.

According to still further features in the described preferredembodiments, at least one of the plurality of cryoprobes is designed andconstructed so as to expand laterally away from the introducer whendeployed. Preferably, at least some of the plurality of cryoprobes aredesigned and constructed to advance, during deployment, in a pluralityof different directions. Also preferably, each cryoprobe deploys fromthe introducer according to a predetermined path, and the plurality ofcryoprobes are designed and constructed to be deployed laterally awayfrom the introducer to form a predetermined arrangement of deployedcryoprobes. The plurality of cryoprobes, designed and constructed toadvance from within the introducer and deploy in a lateral directionaway from a periphery of the introducer, thereby define athree-dimensional cryoablation volume, which may be of predeterminedshape.

According to still further features in the described preferredembodiments, each cryoprobe is retractable and advanceable in and out ofthe introducer. An advancing and retracting member may be operablycoupled to one or more cryoprobe of the plurality of cryoprobes.

According to still further features in the described preferredembodiments, at least one cryoprobe of the plurality of cryoprobes has asharp distal end.

According to still further features in the described preferredembodiments, at least one cryoprobe of the plurality of cryoprobes has ablunt distal end.

According to still further features in the described preferredembodiments, at least one of the plurality of cryoprobes comprises aJoule-Thomson heat exchanger. Preferably, the Joule-Thomson heatexchanger is coupled to a tube through which gasses enter the cryoprobe,the tube has an orifice located at a distal end of the tube, the orificeopens into a sheath which includes a thermally conductive materialdesigned and constructed to conduct heat when the cryoprobe is incontact with a body tissue to be cryoablated. Preferably, theJoule-Thomson heat exchanger comprises a coiled tube housed within thethermally conductive sheath, and the Joule-Thomson heat exchangerfurther comprises a gas supply line on its proximal end and a gas outleton its distal end, the outlet being in fluid communication with achamber.

According to still further features in the described preferredembodiments, at least one of the plurality of cryoprobes comprises aheat-exchanging configuration. The heat exchaning configuration mayinclude a porous matrix, which may include a conduit tunneling throughat least a portion of the porous matrix, and which may include a spiralconduit integrated with the porous matrix.

According to still further features in the described preferredembodiments, at least one of the plurality of cryoprobes comprises athermal sensor for monitoring local temperature conditions in areas inclose proximity to the sensor. Preferably, at least one of the pluralityof cryoprobes further comprises a feedback control system coupled to agas source and to the thermal sensor, the feedback system is responsiveto a detected characteristic from the thermal sensor and serves forcontrolling a rate of delivery of gas from the gas source to thecryoprobe. The thermal sensor is preferably positioned at the distal endof the cryoprobe, and may include a thermocouple.

According to still further features in the described preferredembodiments, at least one of said plurality of cryoprobes comprises ashape memory alloy material. The shape memory alloy material displaysstress induced martensite behavior at a deployed position. The shapememory alloy material is in a non-stress induced martensite state whensaid cryoprobe is positioned in the introducer prior to deployment ofthe cryoprobe outside the introducer. Preferably the shape memory alloymaterial is an alloy of nickel titanium.

According to still further features in the described preferredembodiments, a cross section of each of said plurality of cryoprobes isbetween 0.3 mm and 3 mm.

According to another aspect of the present invention there is provided amethod of cryosurgery comprising: (a) introducing into a body of apatient an introducer having a hollow and a distal portion beingsufficiently sharp so as to penetrate into the body of the patient, thehollow of the introducer containing a plurality of cryoprobes each beingcapable of effecting cryoablation, each of the plurality of cryoprobesis deployable through the distal portion of the introducer; (b)deploying at least one of the plurality of cryoprobes; and (c)cryoablating a tissue of the patient with at least one of the pluralityof cryoprobes.

According to further features in preferred embodiments of the inventiondescribed below, the step of cryoablating a tissue of the patient withat least one of the plurality of cryoprobes is accomplished by supplyinga high-pressure gas to at least one of the plurality of cryoprobes, andcooling the cryoprobe by passing the gas through a Joule-Thomson orificein a Joule-Thomson heat exchanger within the cryoprobe.

According to still further features in the described preferredembodiments, the cryosurgery method further comprises the step ofcooling the gas within the body of the introducer prior to passing thegas through a Joule-Thomson orifice in the Joule-Thomson heat exchangerwithin the cryoprobe.

According to still further features in the described preferredembodiments the cryosurgery method further comprises heating at leastone of the plurality of cryoprobes prior to removing the cryoprobe froma site of cryoablating of a tissue of the patient.

According to still further features in the described preferredembodiments the cryosurgery method further comprises the step ofdeploying at least several cryoprobes, thereby defining a threedimensional cryoablation volume, and cryoablating the volume so defined.Preferably, an imaging device is used to position at least one of theplurality of cryoprobes with respect to a tissue to be cryoablated.Preferably, the imaging device is selected from the group consisting ofan ultrasound device, a computerized tomography (CT) device, a closedmagnetic resonance imaging (MRI) device, an open magnetic resonanceimaging (MRI) device, a fluoroscope device and an X-ray device.

According to still further features in the described preferredembodiments the cryosurgery method further comprises the step ofinducing fast cyclical temperature changes in a deployed cryoprobe, suchthat a temperature of said probe alternates rapidly between atemperature of approximately 0° C. and a temperature below −40° C.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing a method and apparatus forcryoablation that provides for the destruction of a defined volume oftissue, yet minimizes damage to adjacent tissues.

The present invention further successfully addresses the shortcomings ofthe presently known configurations by providing a method of cryoablationusing an apparatus that creates an extended volume of cryoablation yetis contained within a single introducer.

The present invention still further successfully addresses theshortcomings of the presently known configurations by providing anapparatus having an introducer which could be introduced through anoperating channel of a catheter or cystoscope, enabling it to reach theproximity of the region to be treated with a minimum of trauma tointervening tissues.

The present invention yet further successfully addresses theshortcomings of the presently known configurations by providing acryoablation apparatus and method which enables the pre-cooling of aplurality of cryoprobes within a single introducer, such that thepre-cooling stage of a two-stage Joule-Thomson heat exchange process cantake place in close proximity to a second stage of cooling which takesplace within the individual cryoprobes.

Implementation of the method and the apparatus of the present inventioninvolves performing or completing selected tasks or steps manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of preferred embodiments of the method andapparatus of the present invention, several selected steps could beimplemented by hardware or by software on any operating system of anyfirmware or a combination thereof. For example, as hardware, control ofselected steps of the invention could be implemented as a chip or acircuit. As software, control of selected steps of the invention couldbe implemented as a plurality of software instructions being executed bya computer using any suitable operating system. In any case, selectedsteps of the method of the invention could be described as beingcontrolled by a data processor, such as a computing platform forexecuting a plurality of instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 is an introducer for introducing a plurality of cryoprobes into abody for effecting cryoablation, according to the present invention;

FIG. 2 is a is a schematic side view, partially in longitudinalcross-section, of an exemplary cryoprobe according to the presentinvention;

FIG. 3 is a schematic depiction showing mechanisms for control ofdelivery of high-pressure gases to a plurality of Joule-Thomson heatexchangers, according to the present invention; and

FIG. 4 is a detail view of a part of an introducer for introducing aplurality of cryoprobes into a body for effecting cryoablation, showinga Joule-Thomson heat exchanger within the introducer, according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a cryosurgical apparatus and method ofcryosurgery. Specifically, the present invention can be used to effectcryoablation of selected tissues of a patient. In particular, theapparatus and method of the invention provide for the cryoablation oftissues with a minimum of damage to healthy tissues adjacent to thetissues to be cryoablated.

To enhance clarity of the following descriptions, the following termsand phrases will first be defined:

The phrase “heat-exchanging configuration” is used herein to refer tocomponent configurations traditionally known as “heat exchangers”,namely configurations of components situated in such a manner as tofacilitate the passage of heat from one component to another. Examplesof “heat-exchanging configurations” of components include a porousmatrix used to facilitate heat exchange between components, a structureintegrating a tunnel within a porous matrix, a structure including acoiled conduit within a porous matrix, a structure including a firstconduit coiled around a second conduit, a structure including oneconduit within another conduit, or any similar structure.

The phrase “Joule-Thomson heat exchanger” refers, in general, to anydevice used for cryogenic cooling or for heating, in which a gas ispassed from a first region of the device, wherein it is held underhigher pressure, to a second region of the device, wherein it is enabledto expand to lower pressure. A Joule-Thomson heat exchanger may be asimple conduit, or it may include an orifice through which gas passesfrom the first, higher pressure, region of the device to the second,lower pressure, region of the device. It may further include aheat-exchanging configuration, for example a heat-exchangingconfiguration used to cool gasses from the first region of the device,prior to their expansion into the second region of the device. As isdescribed hereinbelow, the expansion of certain gasses (referred toherein as “cooling gases”) in a Joule-Thomson heat exchanger, whenpassing from a region of higher pressure to a region of lower pressure,causes these gasses to cool and may cause them to liquefy, creating acryogenic pool of liquefied gas. This process cools the Joule-Thomsonheat exchanger itself, and also cools any thermally conductive materialsin contact therewith. As further described hereinbelow, the expansion ofcertain other gasses (referred to herein as “heating gasses”) in a JouleThompson heat exchanger causes the gas to heat, thereby heating theJoule-Thomson heat exchanger itself and also heating any thermallyconductive materials in contact therewith.

The principles and operation of a cryosurgical apparatus and methodaccording to the present invention may be better understood withreference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Cryoablation is typically performed in cases where a tissue of a patienthas been diagnosed as undergoing inappropriate, e.g., malignant orbenign, growth or development. Cryoablation might be used, for example,in the case of a malignant tumor, or in the case of a non-malignant masscompressing healthy tissues, thereby disturbing the normal functioningthereof. The operation might typically be performed in tissues of theprostate, kidney, lung, liver, bone, or breast, or in other tissues. Inthese and similar cases, cryoablation may be used to destroy theoffending tissues.

Referring now to the drawings, FIG. 1 illustrates the basic principle ofthe invention herein described. An introducer 100 in accordance with theteachings of the present invention, is designed and constructed so as tobe sufficiently sharp, so as to easily penetrate through body tissue,inflicting minimal damage to nearby tissues. Introducer 100 has a hollow102. Hollow 102 is designed and constructed for containing a pluralityof cryoprobes 104. Each of cryoprobes 104 is capable of being cooled toa low temperature, say −60 to −120° C., or preferably less, and iscapable of freezing tissues, for effecting cryoablation.

A distal portion 106 of introducer 100 is formed with a plurality ofopenings 110. As is further detailed hereinbelow, openings 110 ofintroducer 100 serve for deployment therethrough of a plurality ofcryoprobes 104. Each of cryoprobes 104 contained within introducer 100is deployable outside introducer 100, and in the deployed state iscapable of effecting cryoablation. Hollow 102 may optionally bepartitioned into a plurality of longitudinal compartments 112, eachcompartment 112 is designed and constructed for containing at least one,preferably one, cryoprobe 104. Hollow 102 of introducer 100 optionallyincludes a Joule-Thomson heat exchanger 200 a (described in detailhereinbelow) for pre-heating and pre-cooling at least a portion ofhollow 102, thereby cooling gasses used for heating and cooling ofcryoprobes 104. External sheath 103 of introducer 100 may includethermally insulating material(s), so as to prevent heat exchange betweenhollow 102 of introducer 100 and tissues of the body, when introducer100 is introduced into a body.

The mode of operation of the cryosurgery apparatus and method of thepresent invention involves introducing introducer 100 with its pluralityof cryoprobes 104 contained within hollow 102 into the body of apatient, then, deploying through openings 110 present at distal portion106 of introducer 100 at least one of cryoprobes 104, and cooling thedeployed cryoprobe or cryoprobes 104 to perform cryoablation.

The image of introducer 100 has been expanded in FIG. 1, so as toenhance visibility of details, yet introducer 100 is preferably thin inconstruction, so as to permit its introduction into the body in a mannerthat minimizes damage to tissues present along its penetration path,leading to the intended site of cryoablation. Preferably a cross-sectionof sheath 103 will not exceed 6 mm. In a presently preferred mode ofoperation, cryoprobes 104 are initially positioned within the introducer(i.e., retracted) so that they do not hinder the penetration of theintroducer into the body of the patient. Each cryoprobe 104 is designedand constructed deployable through openings 110 present at distalportion 106 of introducer 100, when distal portion 106 is appropriatelypositioned with respect to a tissue to be cryoablated. An optionaldeploying and retracting member 114, shown in FIG. 1 operably coupled toa cryoprobe 104 a, may be operably coupled to some or all of cryoprobes104. For most applications it will be convenient for cryoprobes 104 tobe provided with sharp distal end 116 to aid in penetration of tissuesduring deployment, yet under some circumstances a cryoprobe 104 with ablunt or rounded distal end 118 may preferably be used.

In a preferred embodiment each of cryoprobes 104 has a cross section ofbetween 0.3 mm and 3 mm. In their undeployed, retracted, state,cryoprobes 104 will fit in the space made available for them withinhollow 102 of introducer 100. This allows introducer 100 to penetratethe body of a patient with little hindrance. Once at the desiredcryoablation site, some or all of cryoprobes 104 are deployed beyondintroducer 100, penetrating further into the body's tissues, at whichtime cryoablation is performed.

In one preferred embodiment of the invention, cryoprobes 104 aredesigned and constructed to advance, during deployment, in a pluralityof different directions. Generally, some of the cryoprobes are designedand constructed so as to expand laterally away from the introducer whendeployed. As cryoprobes 104 so designed and constructed advance fromwithin introducer 100 and deploy in a lateral direction away from theperiphery of introducer 100, they thereby define a three-dimensionalcryoablation volume.

In a preferred embodiment of the present invention, cryoprobes 104 arepartly constructed of shape memory alloy material, such as nitinol, anickel titanium alloy. In typical use, shape memory alloy material usedin cryoprobe 104 displays stress induced martensite behavior whencryoprobe 104 is at its deployed position. Also in typical use, shapememory alloy material used in cryoprobe 104 is in a non-stress inducedmartensite state when cryoprobe 104 is positioned within introducer 100.

The use of shape memory material in the construction of cryoprobes 104results in each cryoprobe being characterized by a particular shape andhence a particular position with respect to the position of introducer100, at the time of its deployment within the body. Cryoprobes 104 maybe deployed substantially to one side of introducer 100, forcryoablation of a volume substantially located alongside introducer 100.Alternatively, introducer 100 may be introduced into a lesion, andcryoprobes 104 may be deployed substantially around introducer 100, forcryoablation of a volume surrounding the position of introducer 100.Generally, deployment of cryoprobes 104 creates a shaped volume ofdeployed cryoprobes, which may be a predefined shaped volume within thebody. Deployed cryoprobes 104 are then cooled so as to performcryoablation, resulting in a shaped volume of cryoablation.

It is a major advantage of the method of the present invention that asurgeon performing a cryoablation can cause the shape and position ofthe cryoablation volume substantially to conform to the shape andposition of the tissues the surgeon desires to cryoablate. The method ofthe present invention permits cryoablation of exactly defined,preselected volumes.

FIG. 1 provides examples of a manner in which cryoprobes deploy fromintroducer 100, each according to a predetermined path, under theinfluence of shape memory alloy. Cryoprobe 104 a, for example, deployslaterally, from a side opening 110 a formed in distal portion 106 ofintroducer 100. Cryoprobe 104 b, on the other hand, deploys in a largelyforward direction, from a forward opening 110 b formed in distal portion106 of introducer 100. Both cryoprobe 104 a and cryoprobe 104 billustrate deployment of a cryoprobe 104 along a predetermined pathcharacterized by being at a specific angle with respect to introducer100. In a slightly different example, shape memory alloy is used tocause a cryoprobe 104 c to deploy according to a predetermined pathcharacterized by a particular radius of curvature. Cryoprobes 104 a, 104b, and 104 c illustrate the general principle that each of a pluralityof cryoprobes 104 may be prepared for deployment and may be deployedeach according to a predetermined path, such that the combination ofdeployed cryoprobes 104 creates a predetermined arrangement of deployedcryoprobes 104, which together define a specific shape at a specificposition in the vicinity of introducer 100. In practice, the arrangementof cryoprobes 104 within introducer 100 may be preselected in accordancewith a predefined cryoablation task.

When deployed cryoprobes 104 are cooled to cryoablation temperatures,e.g., −60° to −160° C., preferably −80° to −120° C., the cooled volumesprovided by each of the deployed cryoprobes 104 combine to produce ashaped cooled volume within which cryoablation is effected. This methodof arranging and deploying the cryoprobes thus creates athree-dimensional cryoablation volume of a predetermined size and shape.

According to a preferred method of operation, diagnostic procedures suchas medical imaging and computer simulation are used in advance of thecryosurgery operation to approximately determine the position and shapeof the tissues to be cryoablated and a configuration of cryoprobes 104which, when deployed, will define a similar shape. Cryoprobes 104 arethen selected, prepared, and placed within introducer 100 in such amanner that when cryoprobes 104 are deployed they will approximatelyform a predetermined shape which appropriately conforms to the diagnosedshape of the tissues to be cryoablated.

In a currently preferred method of operation according to the presentinvention, medical imaging equipment such as X-ray, fluoroscope,computerized tomography (CT), ultrasound, MRI (open MRI in particular),or other forms of imaging equipment is used during the operation toguide the introduction of introducer 100 into the body of a patient, toguide the placement of introducer 100 in the vicinity of the siteintended for cryoablation, and to guide the deployment of cryoprobes 104at that site, thereby ensuring that the actual shape and placement ofdeployed cryoprobes 104 appropriately corresponds to the placement andshape of the tissues to be cryoablated. Cooling of the deployedcryoprobes 104 is then used to cryoablate a volume of tissueapproximately corresponding to the predetermined shape intended to becryoablated. This method has the advantage of minimizing the destructiveeffect of the cryoablation procedure on healthy tissues in the vicinityof the cryoablated tissues.

FIG. 2 illustrates an individual cryoprobe 104 according to a preferredembodiment of the present invention. Cryoprobe 104 preferably includeselongated housing 3 having a distal operating head 4 for penetratingthrough tissues of a patient during deployment.

Distal operating head 4 is connected to elongated housing 3 by means ofan elongated member 5 substantially thin in cross section for allowingdeployment into the tissues of a body. Elongated housing 3, elongatedmember 5, and other elements of cryoprobe 104 may include shape memoryalloy, as described above.

As shown in FIG. 2, cryoprobe 104 preferably includes a first passageway10 extending along its length for providing gas of high-pressure to aJoule-Thomson heat exchanger 200 b located at distal operating head 4,and a second passageway 16 for evacuating gas from the operating head toatmosphere. First passageway 10 is preferably in the form of asubstantially thin tubular element extending along elongated housing 3,elongated member 5, and a portion of operating head 4. As shown in thefigure, the portion of first passageway 10 extending along elongatedhousing 3 is preferably in the form of a spiral tube 14 a wrapped aroundsecond passageway 16, thereby constituting a heat-exchangingconfiguration 40 a for exchaning heat between spiral tube 14 a andsecond passageway 16. The portion of first passageway 10 extending alongelongated member 5 and portion of operating head 4 is preferably in theform of a straight tube 14 b received within second passageway 16.Further as shown in the figure, tube 14 b preferably penetrates intosecond passageway 16 substantially adjacent the connection of elongatedmember 5 and housing 3.

Further, elongated housing 3 preferably includes a third passageway 20enclosing first and second passageways 10 and 16, which third passagewayforming a heat-exchanging configuration 40 b in the form of a heatexchanging chamber for precooling or preheating gas flowing withinspiral tube 14 a before it arrives to operating head 4. Third passageway20 preferably merges with second passageway 16 at the upper end ofelongated housing 3 to form a common passageway 22 for releasing gas toatmosphere.

In an alternative construction, heat exchanging configuration 40 b maybe formed as a porous matrix 42 filling or partially filling passageway20, with spiral tube 14 a being formed as a spiral conduit integratedinto porous matrix 42 and second passageway 16 being formed as astraight conduit tunnelling through porous matrix 42.

As shown in the figures, the various passageways of the device areenclosed by an insulating chamber 24 extending along housing 3 andelongated member 5.

Preferably, a device according to the present invention provideseffective cooling or heating by using Joule-Thomson heat exchangers.Thus, first passageway 10 preferably includes a plurality of orificesfor passage of high-pressure gas therethrough so as to cool or heatselective portions of the device, depending on the type of gas used.Gases that may be used for cooling include argon, nitrogen, air,krypton, CF₄, xenon, N₂O, or any mixture of gases, and are referred toherein as “cooling gasses”. High pressure cooling gasses are cooled byexpansion when passing through a Joule-Thomson orifice, therebyproviding their cooling effect. Gases that may be used for heatinginclude helium or any mixture of gases, and are referred to herein as“heating gasses.” Heating gasses have an inversion temperature lowerthan temperature obtained by liquefaction of cooling gas.

According to the embodiment shown in FIG. 2, a primary Joule-Thomsonheat exchanger 200 b is located at distal operating head 4, which heatexchanger including: an orifice 6 located preferably at the end ofstraight tube 14 b, and a chamber 7 defined by the inner walls of head4. When a high-pressure cooling gas such as argon passes through orifice6 it expands, causing it to cool and in some cases to liquify so as toform a cryogenic pool within chamber 7 of operating head 4. The cooledexpanded gas, and the cryogenic pool of liquefied gas which may form,effectively cool outer sheath 8 of operating head 4. Outer sheath 8 ispreferably made of a heat conducting material such as metal foreffectively freezing body tissue so as to produce the desiredcryoablation effect. When a high-pressure heating gas such as heliumexpands through orifice 6 it heats chamber 7 of operating head 4,thereby heating outer sheath 8 of the operating head. Such heating ofthe operating head may be used for preventing sticking of the device tothe tissue being cryoablated.

According to a preferred embodiment of the present invention cryoprobe104 preferably includes a plurality of Joule-Thomson heat exchangers 200c for effectively precooling or preheating the gas flowing within firstpassageway 10. According to the embodiment shown in FIG. 2, secondaryJoule-Thomson heat exchanger 200 c is located within housing 3, includesa chamber 21 defined by the inner walls of passageway 20, and preferablyincludes an orifice 18 located preferably at the lower end of spiraltube 14 a. The optional spiral construction of spiral tube 14 a isdesigned and constructed as heat-exchanging configuration 40 a,facilitating the exchange of heat between spiral tube 14 a and secondpassageway 16, and as heat-exchanging configuration 40 b facilitatingthe exchange of heat between spiral tube 14 a and passageway 20.

When a high-pressure cooling gas such as argon passes through orifice 18it expands and is thereby cooled. The expanded gas may liquefy so as toform a cryogenic pool within chamber 21. The cooled expanded gas, and acryogenic pool of liquefied gas which may form, effectively coolpassageway 20, thereby precooling the gas flowing within spiral tube 14a. When a high-pressure heating gas such as helium expands throughorifice 18 it heats chamber 21 and passageway 20, thereby effectivelypreheating the gas flowing within spiral tube 14 a.

Thus, gas flowing through spiral tube 14 a is effectively pre-cooled orpre-heated by exchanging heat with third passageway 20. Furthermore, thegas flowing through spiral tube 14 a and strait tube 14 b exchanges heatwith second passageway 16 which contains cooled (or heated) gas comingfrom operating head 4.

A cryosurgery device according to the present invention enables toeffectively and quickly produce the desired freezing effect and toquickly inverse from cooling to heating so as to prevent sticking of theoperating head to the tissue.

A cryosurgery device according to the present invention also enables toinduce fast cyclical temperature changes in a deployed cryoprobe, suchthat a temperature of the probe alternates rapidly between a temperatureof approximately 0° C. and a temperature below −40° C. This cryosurgicaltechnique has been found useful in a variety of cryosurgical situations.

According to another embodiment (not shown), first passageway 10 mayinclude a plurality of orifices located along spiral tube 14 a andstrait tube 14 b. Further, a device according to the present inventionmay include a plurality of Joule-Thomson heat exchangers for cooling orheating selected portions of the device, wherein each Joule-Thomson heatexchanger includes a plurality of orifices.

The heating mechanisms heretofore described, and the cooling mechanismheretofore described, may be separate mechanisms both contained withincryoprobe 104, yet in a preferred embodiment these mechanisms are acombined heating/cooling mechanism. First passageway 10 is designed andconstructed so as to be coupleable to a first gas source, supplying ahigh-pressure cooling gas, and also to be coupleable to a second gassource supplying high-pressure heating gas. Thus coolable cryoprobe 104may also be heatable.

Cryoprobe 104 preferably further comprises control elements forregulating the flow of gas from the first gas source and the second gassource. In a preferred embodiment, cryoprobe 104 includes a thermalsensor 30, such as, for example, a thermocouple, for monitoring thetemperature within chamber 7 of operating head 4 at the distal portionof cryoprobe 104. An additional thermal sensor 32 may also be used tomonitor temperature within chamber 21, or alternatively be placed atsome other convenient position within cryoprobe 104 for monitoring localtemperature conditions there.

FIG. 3 is a schematic drawing showing mechanisms for control of deliveryof high-pressure gases to the plurality of Joule-Thomson heat exchangers200 of cryoprobes 104 and/or introducer 100 employed in context of thepresent invention. Thus, heat exchangers 200 of FIG. 3 schematicallyrepresent individual Joule-Thomson heat exchange mechanisms hereindescribed, such as a Joule-Thomson heat exchanger 200 a of introducer100 shown in FIG. 1 and in FIG. 4, and Joule-Thomson heat exchangers 200b and 200 c of individual cryoprobes 104 shown in FIG. 2.

Each Joule-Thomson heat exchanger 200 is coupled to a passageway 202 forsupplying high-pressure gas thereto. A passageway 202, for example,would be coupled to each gas input passageway 10 of individualcryoprobes 104, as shown in FIG. 2. A passageway 202 would similarly becoupled to the gas input passageway 310 of heat exchanger 200 a, shownin detail in FIG. 4.

Each heat exchanger 200 also optionally includes a thermal sensor whichmonitors temperatures therewithin or in its vicinity. Each such thermalsensor connects to an electrical feedback connection 204 which therebyreceives information about the temperatures within heat exchangers 200.Electrical feedback connections 204 may be direct electricalconnections, or other connections capable of transmitting data, such asinfra-red connections. Thus, feedback connections 204 electricallyconnect with thermal sensors 30 and 32 of individual cryoprobes 104 asshown in FIG. 2, and with thermal sensor 316 of introducer 100 as shownin FIG. 4.

In FIG. 3, high-pressure heating gas source 206 supplies gas throughcontrol valve 208 and through a one-way valve 205 to common gas feedline 220. Optional compressor 209 may be used to compress gas fromsource 206 to pressures higher than that supplied by source 206.Similarly, high-pressure cooling gas source 216 supplies gas throughcontrol valve 218 and one-way valve 205 to common gas feed line 220.Optional compressor 219 may be used to compress gas from source 216 topressures higher than that supplied by source 216.

Optional control unit 230 is for controlling valves 208 and 218, therebycontrolling a flow of gas from the gas sources into common gas feed line220. Control unit 230 is also for controlling individual valves 232,thereby regulating the flow of gas into each Joule-Thomson heatexchanger 200.

Control unit 230 receives control instructions from a control input unit240, which may include an operator's interface and optionalcomputational and memory systems for supplying pre-programmedinstructions. Control input unit 240 may connect directly to controlunit 230, or control input unit 240 may be more or less remote fromcontrol unit 230 and communicate with control unit 230 using remotecommunication, such as radio or infra-red communication, or some otherform of data communication. Control unit 230 may further communicatewith, and receive control instructions from, a plurality of controlinput units 240.

Control unit 230 also receives feedback information from feedbackconnections 204 reporting temperatures within heat exchangers 200 (e.g.,from thermal sensors 30, 32 and 316) or from other parts of theapparatus. Control unit 230, under instructions from control input unit240 relating to the desired temperatures, opens and closes valves 208,218, and 232 to control the flow of heating and cooling gasses to heatexchangers 200.

Joule-Thomson heat exchangers 200 heat and cool individual cryoprobes104. Optionally, Joule-Thomson heat exchanger 200 a of introducer 100further preheats heating gasses and precools cooling gasses as they passthrough Joule-Thomson heat exchanger 200 a of introducer 100 on theirway towards the Joule-Thomson heat exchangers 200 b and 200 c ofindividual to cryoprobes 104.

Optional Joule-Thomson heat exchanger 200 a, which appears in asimplified form in FIG. 1, is presented in additional detail in FIG. 4,according to a preferred embodiment of the present invention.

FIG. 4 shows a portion of an introducer 100. Passageways 10, which servefor passing gas from high-pressure gas sources outside introducer 100 tocryoprobes 104, are situated near or within a chamber 304 within hollow102 of introducer 100. Gas input passageway 310 provides high-pressurecooling or heating gasses which pass from passageway 310 throughJoule-Thomson orifice 312, and expand into chamber 304. Cooling gassespassing from passageway 310 through Joule-Thomson orifice 312 expand andare thereby cooled and may liquefy. Cooling gasses cooled by expansion,and a cryogenic pool of liquefied gasses which may form, cool chamber304. Heating gasses, which have an inversion temperature lower than thetemperature obtained by liquefaction of the cooling gasses, pass frompassageway 310 through Joule-Thomson orifice 312 and heat chamber 304.The gasses are subsequently exhausted to the atmosphere throughpassageway 314. Optional thermal sensor 316, which may be athermocouple, monitors temperatures in chamber 304 and connects toelectrical feedback connection 204 shown in FIG. 3.

In a preferred embodiment, heat exchanger 200 a includes aheat-exchanging configuration 40 c for facilitating exchange of heatbetween incoming gasses entering heat exchanger 200 a through passageway310 and exhaust gasses being exhausted to the atmosphere throughpassageway 314 after passing through Joule-Thomson orifice 312. In thisembodiment passageway 310 for incoming gasses and passageway 314 forexhaust gasses are constructed of heat conducting material, such as ametal, and are constructed contiguous to each other, or wrapped onearound the other. In an alternative construction of heat-exchangingconfiguration 40 c, passageway 314 is implemented as a porous matrix 320through which expanded gasses are exhausted to atmosphere. In thisconstruction, passageway 310 is implemented as conduit 322 for incominggasses formed within porous matrix 320. Conduit 322 may be formed as astraight conduit tunneling through porous matrix 320, or it may beformed as a spiral conduit integrated with porous matrix 320.

Heating gasses being exhausted through passage 314 after having passedthrough Joule-Thomson orifice 312 are hotter than incoming heatinggasses entering through passageway 310. Consequently, exchange of heatbetween passageway 310 and passageway 314 has the effect of preheatingincoming heating gasses, thereby enhancing efficiency of the apparatus.

Similarly, cooling gasses being exhausted through passage 314 afterhaving passed through Joule-Thomson orifice 312 are colder than incomingcooling gasses entering through passageway 310. Consequently, exchangeof heat between passageway 310 and passageway 314 has the effect ofprecooling incoming cooling gasses, thereby enhancing efficiency of theapparatus.

Passageways 10 are preferably made of a thermally conducting material,such as a metal. Consequently, heating or cooling chamber 304 pre-heatsor pre-cools the gasses passing through passageways 10 towardscryoprobes 104. Thus, the arrangement here described constitutes aheat-exchanging configuration 40 d, for facilitating exchange of heatbetween heating and cooling chamber 304 and gas passing throughpassageways 10. In an alternate construction, heat-exchangeconfiguration 40 d is formed by implementing a portion of passageways 10as either straight or spiral conduits tunneling through a porous matrix46 occupying a portion of chamber 304. In yet another alternativearrangement, cryoprobes 104 themselves pass through chamber 304,resulting a similar pre-heating or pre-cooling effect. Chamber 304 mayalso be designed and constructed such that heating and cooling ofchamber 304 has the effect of heating and cooling all or most of hollow102 of introducer 100, and, as a result, all or most of the contentsthereof.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1. A cryosurgery apparatus comprising a sheath forming a first hollowand having a distal portion, said distal portion being sufficientlysharp so as to penetrate into a body, said first hollow being designedand constructed for containing a plurality of cryoprobes each of saidcryoprobes being operable to be deployed through openings in said sheathinto tissues surrounding said sheath, and at least some of saidcryoprobes being operable to cryoablate tissues external to said sheathwhen so deployed.
 2. The apparatus of claim 1, wherein said sheathcomprises thermal insulation designed and constructed so as to hinderthe passage of heat between said hollow and tissues of the body, whensaid sheath is positioned within the body.
 3. The cryosurgery apparatusof claim 1, wherein said hollow is partitioned into a plurality oflongitudinal compartments, each of said plurality of longitudinalcompartments is designed and constructed for containing at least one ofsaid plurality of cryoprobes.
 4. The cryosurgery apparatus of claim 1,further comprising a cooling device designed and constructed to coolsaid hollow.
 5. The cryosurgery apparatus of claim 1 further comprisinga heating device designed and constructed to heat said hollow.
 6. Thecryosurgery apparatus of claim 4, further comprising a heating devicedesigned and constructed to heat said hollow.
 7. The cryosurgeryapparatus of claim 6, wherein said cooling device and said heatingdevice are a combined heating/cooling device.
 8. The cryosurgeryapparatus of claim 7, wherein said combined heating/cooling device is aJoule-Thomson heat exchanger.
 9. The cryosurgery apparatus of claim 4,wherein said cooling device is a Joule-Thomson heat exchanger.
 10. Thecryosurgery apparatus of claim 1, further comprising a cooling devicefor pre-cooling gasses which are passed through at least a portion ofsaid hollow and are subsequently delivered to at least one of saidcryoprobes.
 11. The cryosurgery apparatus of claim 10, wherein saidcooling device is a Joule-Thomson heat exchanger.
 12. The cryosurgeryapparatus of claim 1, further comprising a heating and cooling devicefor pre-heating and pre-cooling gasses which are passed through at leasta portion of said hollow and are subsequently delivered to at least oneof said cryoprobes.
 13. The cryosurgery apparatus of claim 12, whereinsaid heating and cooling device is a Joule-Thomson heat exchanger. 14.The cryosurgery apparatus of claim 1, further comprising a thermalsensor for monitoring a temperature in said hollow.
 15. The cryosurgeryapparatus of claim 14, wherein said thermal sensor is a thermocouple.16. The apparatus of claim 1, further comprising said plurality ofcryoprobes.
 17. The cryosurgery apparatus of claim 16, wherein at leastone of said plurality of cryoprobes is coolable.
 18. The cryosurgeryapparatus of claim 17, wherein said coolable cryoprobe is also heatable.19. The cryosurgery apparatus of claim 16, wherein at least one of saidplurality of cryoprobes comprises a Joule-Thomson heat exchanger havinga Joule-Thomson orifice, for changing a temperature of said cryoprobe.20. The cryosurgery apparatus of claim 16, wherein at least one of saidplurality of cryoprobes comprises a distal operating head which includesa thermally conductive outer shell having a closed distal end and achamber formed within the shell, said operating head being adapted to beinserted into a body and to effect cryoablation thereat.
 21. Thecryosurgery apparatus of claim 20, wherein said chamber serves as areservoir for housing a fluid in contact with at least a portion of saidouter shell of said distal operating head.
 22. The cryosurgery apparatusof claim 16, wherein at least one of said plurality of cryoprobes isdesigned and constructed coupleable to at least one high-pressure gassource.
 23. The apparatus of claim 16, wherein at least one of saidplurality of cryoprobes comprises a first Joule-Thomson heat exchangeroperable to cool said cryoprobe to cryoablation temperatures.
 24. Theapparatus of claim 23, further comprising a second Joule-Thomson heatexchanger in said sheath, operable to cool said hollow.
 25. Theapparatus of claim 23, further comprising a second Joule-Thomson heatexchanger within said sheath and external to said cryoprobes, saidsecond Joule-Thomson heat exchanger being operable to cool ahigh-pressure gas delivered to said first Joule-Thomson heat exchanger.26. The apparatus of claim 23, further comprising a first heatexchanging configuration operable to facilitate exchange of heat betweenhigh-pressure gas delivered to said first Joule-Thomson heat exchanger,and low-pressure gas depressurized by expansion through a first JouleThomson orifice in said first Joule-Thomson heat exchanger.
 27. Theapparatus of claim 26, wherein said first heat-exchanging configurationcomprises a porous matrix.
 28. The apparatus of claim 27, wherein saidporous matrix further comprises a conduit tunneling through at least aportion of said porous matrix.
 29. The apparatus of claim 27, whereinsaid porous matrix comprises a conduit formed as a spiral integratedinto said porous matrix.
 30. The apparatus of claim 25, furthercomprising a second heat exchanging configuration operable to facilitateexchange of heat between high-pressure gas delivered to said secondJoule-Thomson heat exchanger, and low-pressure gas depressurized byexpansion through a second Joule Thomson orifice in said secondJoule-Thomson heat exchanger.
 31. The apparatus of claim 30, whereinsaid second heat-exchanging configuration comprises a porous matrix. 32.The apparatus of claim 31, wherein said porous matrix further comprisesa conduit tunneling through at least a portion of said porous matrix.33. The apparatus of claim 31, wherein said porous matrix comprises aconduit formed as a spiral integrated into said porous matrix.
 34. Theapparatus of claim 1, wherein at least one of said cryoprobes isoperable to be controllably connected to a first source of high-pressuregas.
 35. The cryosurgery apparatus of claim 34, wherein said firsthigh-pressure gas source is a source of at least one gas selected from agroup consisting of high-pressure argon, high-pressure nitrogen,high-pressure air, high-pressure krypton, high-pressure CF4,high-pressure N2O and high-pressure carbon dioxide.
 36. The apparatus ofclaim 34, wherein said first gas source provides a gas that cools whenexpanding after passage through a Joule-Thomson orifice.
 37. Theapparatus of claim 34, wherein said sheath is operable to becontrollably connected to said first source of high-pressure gas. 38.The apparatus of claim 34, wherein said at least one cryoprobe isfurther operable to be controllably connected to a second source ofhigh-pressure gas.
 39. The cryosurgery apparatus of claim 38, whereingas provided by said second gas source has an inversion temperaturelower than the temperature obtained by liquefaction of gas provided bysaid first gas source.
 40. The cryosurgery apparatus of claim 38,wherein said second high-pressure gas source is a source ofhigh-pressure helium.
 41. The cryosurgery apparatus of claim 38, furthercomprising control elements for regulating a flow of gas from each ofsaid first gas source arid said second gas source.
 42. The cryosurgeryapparatus of claim 38, designed and constructed so as to facilitateexchange of heat between two temperature states of gas from said firsthigh-pressure gas source, gas in a first state being at a firsttemperature prior to passing through said first Joule-Thomson orifice,and gas in a second state being at a second temperature subsequent topassing through said first Joule-Thomson orifice.
 43. The apparatus ofclaim 38, wherein said sheath is operable to be controllably connectedto said first source of high-pressure gas and to said second source ofhigh-pressure gas.
 44. The apparatus of claim 34, wherein said at leastone cryoprobe comprises a first Joule-Thomson heat exchangercontrollably connected to said first gas source, said firstJoule-Thomson heat exchanger is operable to cool said cryoprobe tocryoablation temperatures.
 45. The apparatus of claim 44, wherein saidfirst Joule-Thomson heat exchanger is controllably connected to saidsecond gas source, and said first Joule-Thomson heat exchanger isoperable to heat said cryoprobe.
 46. The apparatus of claim 37, whereinsaid sheath further comprises a second Joule-Thomson heat exchangerexternal to said plurality of cryoprobes, said second Joule-Thomson heatexchanger is controllably connected to said first source of compressedgas and is operable to cool said hollow.
 47. The cryosurgery apparatusof claim 38, further comprising control elements for regulating a flowof gas from each of said first gas source and said second gas source.48. The cryosurgery apparatus of claim 46, designed and constructed soas to facilitate exchange of heat between two temperature states of gasfrom said first high-pressure gas source, gas in a first state being ata first temperature prior to passing through said second Joule-Thomsonorifice, and gas in a second state being at a second temperaturesubsequent to passing through said second Joule-Thomson orifice.
 49. Theapparatus of claim 46, wherein said second Joule-Thomson heat exchangeris controllably connected to a second source of compressed gas, and isoperable to heat said hollow.
 50. The cryosurgery apparatus of claim 1,further comprising a heating and cooling device for pre-heating andpre-cooling gasses which are passed through at least a portion of saidfirst hollow and are subsequently delivered to at least one of saidcryoprobes.
 51. The cryosurgery apparatus of claim 50, furthercomprising a heat-exchanging configuration for exchanging heat between agas passed to said heating and cooling device.
 52. The cryosurgeryapparatus of claim 1, wherein at least one of said plurality ofcryoprobes comprises a first thermal sensor for monitoring a temperaturein said cryoprobe, and wherein said hollow comprises a second thermalsensor for monitoring a temperature in said hollow.
 53. The cryosurgeryapparatus of claim 52, wherein at least one of said first thermal sensorand said second thermal sensor is a thermocouple.
 54. The cryosurgeryapparatus of claim 1, wherein said distal end of said sheath is formedwith a plurality of openings for deployment therethrough of saidplurality of cryoprobes.
 55. The apparatus of claim 1, wherein at leastone of said plurality of cryoprobes is designed and constructed so as toexpand laterally away from said sheath when deployed.
 56. The apparatusof claim 55, wherein each of said plurality of cryoprobes deploys fromsaid sheath each according to a predetermined path.
 57. The cryosurgeryapparatus of claim 1, wherein said plurality of cryoprobes are designedand constructed to be deployed laterally away from the sheath to form apredetermined arrangement of deployed cryoprobes.
 58. The cryosurgeryapparatus of claim 1, wherein said plurality of cryoprobes are designedand constructed to advance from within said sheath and deploy in alateral direction away from a periphery of said sheath, thereby defininga three-dimensional cryoablation volume.
 59. The cryosurgery apparatusof claim 58, wherein at least some of said plurality of cryoprobes aredesigned and constructed to advance, during deployment, in a pluralityof different directions.
 60. The cryosurgery apparatus of claim 58,wherein said three-dimensional cryoablation volume is of a predeterminedshape.
 61. The cryosurgery apparatus of claim 1, wherein each of saidcryoprobes is retractable and advanceable in and out of said sheath. 62.The cryosurgery apparatus of claim 1, further comprising an advancingand retracting member operably coupled to at least one cryoprobe of saidplurality of cryoprobes.
 63. The cryosurgery apparatus of claim 1,wherein at least one cryoprobe of said plurality of cryoprobes has asharp distal end.
 64. The cryosurgery apparatus of claim 1, wherein atleast one cryoprobe of said plurality of cryoprobes has a blunt distalend.
 65. The cryosurgery apparatus of claim 34, wherein at least one ofsaid plurality of cryoprobes further comprises a thermal sensor andfeedback control system coupled to said first gas source and to saidthermal sensor, said feedback system is responsive to a detectedcharacteristic from said thermal sensor and serves for controlling arate of delivery of gas from said gas source to said cryoprobe.
 66. Thecryosurgery apparatus of claim 65, wherein said thermal sensor ispositioned at the distal end of said cryoprobe.
 67. The cryosurgeryapparatus of claim 65, wherein said thermal sensor includes athermocouple.
 68. The cryosurgery apparatus of claim 1, wherein at leastone of said plurality of cryoprobes comprises a shape memory alloymaterial.
 69. The cryosurgery apparatus of claim 68, wherein said shapememory alloy material displays stress induced martensite behavior at adeployed position.
 70. The cryosurgery apparatus of claim 68, whereinsaid shape memory alloy material is in a non-stress induced martensitestate when said cryoprobe is positioned in said sheath prior todeployment of said cryoprobe outside said sheath.
 71. The cryosurgeryapparatus of claim 68, wherein said shape memory alloy material is analloy of nickel titanium.
 72. The cryosurgery apparatus of claim 1,wherein a cross section of each of said plurality of cryoprobes isbetween 0.3 mm and 3 mm.